Aircraft wing with a wing tip device and a strut

Abstract

An aircraft wing (1) has a wing tip device (3) joined thereto. The root (7) of the wing tip device (3) is joined to the tip of the wing (1) at a first connection (11). An external strut (9) extends between the wing (1) and the wing tip device (3), the strut (9) being joined to the wing (1) at a second connection (13). The second connection (13) is inboard of the first connection, such that loadings on the wing tip device (3) generated during use, are transferred, via the strut (9), to a location on the wing (1) that is inboard of where the root (7) of the wing tip device (3) is joined to the tip of the wing.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to an aircraft wing with a wing tip device and strut extending between the wing and the wing tip device, an aircraft incorporating such a wing, and to methods of modifying an aircraft wing to install a wing tip device.[0002]In recent years, it has become increasingly desirable to install wing tip devices to aircraft wings. It is known to install wing tip devices onto aircraft that are already in use (for example a wing tip device may be added during a major maintenance overhaul of the aircraft). This is commonly referred to as “retro-fitting” the wing tip device. It is also known to install wing tip devices during manufacture of a new aircraft, but where that aircraft was not originally designed to have the wing tip device installed, thereby enabling incremental improvements to existing aircraft designs. This is commonly referred to as “forward-fitting” the wing tip device.[0003]A problem when attempting to retro-fit or ...

AI Technical Summary

Benefits of technology

[0008]By using a strut between the wing tip device and the wing, at least some of the loadings on the wing tip device can be transferred to a location inboard of the connection between the wing / wing tip device. This inboard location can be better suited to cope with the loadings (for example the wing box may be thicker at that inboard location than at the wing tip and / or more suited to the use of preferred fasteners, such as shear bolts). Thus, for a given size of wing tip device, fewer structural reinforcements to the wing may be required, and / or for a given level of reinforcement, a larger, more effective wing tip device may be installed (relative to an arrangement in which the wing tip device only being connected at the wing tip).

[0010]The invention may enable the first connection to be weaker, and therefore lighter, than would otherwise be required in the absence of the strut. The first connection is preferably unsuitable for transferring the loadings on the wing tip device to the wing, in the absence of the strut. For example the first connection may be too weak to safely be relied upon, in isolation, to transfer the loadings. Such an arrangement may facilitate weight savings, without compromising safety.

[0013]The first connection may be substantially unable to support a bending moment across it. For example, the first connection may be a pin-joint. The first connection is preferably unable to support a bending moment generated by the weight of the wing tip device acting around the connection. Such an arrangement is beneficial because during installation, the wing tip device may be connected to the wing at its root (i.e. at the first connection) and then be allowed to hang down under its own weight. Thus the wing tip device does not have to be supported by an auxiliary structure whilst the strut is installed. This facilitates relatively straightforward installation of the wing tip device and of the strut.

[0026]By fitting the wing tip device using such a method, at least some of the loadings on the wing tip device during use, can be transferred to a location inboard of the connection between the wing / wing tip device (i.e. the first connection). This inboard location can be better suited to cope with the loadings (for example the wing box may be thicker at that inboard location than at the wing tip). Thus, for a given size of wing tip device, fewer structural re-enforcements to the wing may be required, and / or for a given level of re-enforcement, a larger wing tip device may be installed (relative to an arrangement in which the wing tip device only being connected at the wing tip).

[0029]The first connection may be substantially unable to support a bending moment across it. The method may comprise the step of joining the root of the wing tip device to the tip of the wing at a first connection, and subsequently allowing the wing tip device to hang from the first connection prior to the strut being fitted to extend between the wing and the wing tip device. Such an arrangement facilitates a relatively easy installation of the wing tip device. The wing tip device may freely hang below the first connection. The wing tip device may be arranged to be partially supported when hanging from the first connection; for example it may be partially supported such that it is not freely hanging, but such that the moment arm, created by its weight acting around the first connection, is relatively small.

Problems solved by technology

A problem when attempting to retro-fit or forward-fit a wing tip device is that the wing (to which the tip devices is being fitted) was not originally designed to receive the wing tip device.

In both these arrangements, it can be difficult to efficiently distribute the loads generated by the wing tip device during use.

This problem is especially acute for large wing tip devices (which are becoming increasingly popular).

This can add weight and / or complexity to the process of retro-fitting or forward-fitting the wing tip device.

Furthermore, the scope for modifying the structure of the wing is often very limited, so the structural reinforcements are often sub-optimal, compared to if they had been able to be incorporated into the wing during the initial design process.

However, this arrangement is not really suitable for a retro-fit or a forward fit application, because the structural modifications to the wing are too significant.

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